1. Field of the Invention
This invention relates to an information retrieval system and, more particularly, to a system for retrieving a large quantity of image information.
2. Description of the Prior Art
As a method for filing the image information by storing the image information, such as document or photographs, and calling out desired image information when it is needed, it is known to file the paper carrying the image information or the copy sheet of the original image in a binder or the like for storage on a shelf. This is extensively utilized filing method basically does not need mechanical or electronic devices as the information may be searched by direct visual inspection. The operation of turning over leaves may be performed speedily and intuitively. To find a particular page in a volume of a file, pages are turned rapidly when to search for a candidate page similar to the particular page based on rough visual impressions received from the pages as they are turned over one after another. During or after the operation of turning over the pages of the file, the contents of the particular candidate page are read roughly for ascertaining whether the candidate page is the desired particular page. This searching method is effective even when the title or the keyword of the particular page is unclear or when the table of contents or the index is incomplete. There are many instances wherein one has to resort to this cumbersome retrieval method of turning over pages of the file one after another.
Directly filed paper sheets also take up much space while being heavy and difficult to handle. Alternative filing systems photograph the documents and store the image information such as on a microfilm or optically reading the documents and recording the image information on a recording medium such as a magneto-optical disc in a digital form have been developed and used extensively. These filing systems are more convenient and compact than the system of directly binding paper sheets because the space needed for storing the same amount of the information is significantly diminished.
However, in a filing system employing the abovementioned microfilm, the contents of the stored information cannot be checked without using a film viewer or like similar device. Although page turning may be performed speedily with the use of a film viewer, it is not possible to record many pages on one film; thus, the retrieval speed on the whole is lowered because of the time-consuming operation is required for film re-loading. In addition, since the pages are sequentially arranged on each film, film feed time is increased if it is desired to check the last page on the film starting from the leading end of the film by a viewer.
On the other hand, while it is possible with the electronic image filing to store a large quantity of the image information, the stored information cannot be grasped intuitively unless a disc reproducing apparatus or a CRT display is used for checking the contents of the information, preventing a speedy turning over of the leaves.